A liquid crystal display device has at least a backlight unit having a light source, a liquid crystal cell having a liquid crystal display element, and two polarizing plates disposed at anteroposterior positions in the direction of transmission of the light emerging from the liquid crystal cell. Normally, the liquid crystal display element controls the amount of light to be transmitted among the light emitted from the backlight unit for every pixel thereby displaying an image.
Such a conventional liquid crystal display device includes a backlight unit which is provided with a case 21 having a surface opening and having an internal peripheral surface that exhibits a light reflection effect and a plurality of cold cathode fluorescent lamps (CCFLs) 22 disposed in parallel in the case 21, as shown in FIG. 12, for example. A light diffusion plate 3 is mounted so as to close the opening of the case 21. A prism film 40 is disposed so as to overlap the light-exiting surface of the light diffusion plate 3 (refer to Patent Literature 1, for example).